t 


Technical  Series,  No.  24. 

U.  S.  DEPARTMENT  OF   AGRICULTURE, 

BTJRE^TJ    OW    KlSrXOMlOLOGJ-Y. 

L.  0.   HOWARD,   Entomologist  and   Chief  of  Bureau. 


THE  LIFE  HISTORY  OF  THE  ALDER 
BLIGHT  APHIS. 


THEO.  PERGAXDE, 

Assistant. 


Issued  April  29,  1912. 


WASHINGTON: 

GOVERNMENT   PRINTING  OFFICE. 

1912. 


Technical  Series,  No.  24. 

U.  S.  DEPARTMENT  OF   AGRICULTURE, 

IBTJRE^TJ    OW    ENTOMOLOGY. 
L.  0.  HOWARD,   Entomologist  and   Chief  of  Bureau. 


THE  LIFE  HISTORY  OF  THE  ALDER 
BLIGHT  APHIS. 


BY 


THEO.  PERGAXDE, 
Assistant. 


Issued  April  29,  1912. 


WASHINGTON: 

GOVERNMENT  PRINTING  OFFICE. 

1912. 


BUREAU  OF  ENTOMOLOGY. 

L.  O.  HOWARD,  Entomologist  and  Chief  of  Bureau. 

C.  L.  Marlatt,  Entomologist  and  Acting  chief  in  Absence  of  Chief. 

R.  S.  Clifton,  Executive  Assistant. 

W.   F.  Tastet,   Chief  Clerk. 

F.  II.  Chittenden,  in  chargeof  truck  crop  and  stored  product  insect  investigations. 

A.  D.  Hopkins,  /'//  charge  of  forest  inset  investigations. 

W.  I).  Hunter,  in  charge  of  southern  field  crop  insect  investigations. 

V.  M.  Webster,  in  charge  of  cereal  and  forage  insect  investigations, 

A.  L.  QUAINTAN(  i.  in  charge  of  deciduous  fruit  insect  investigations. 

E.  V.  Phillips,  in  charge  of  bee  culture. 

I).  M.  Rogers,  in  charge  of  preventing  spread  of  moths,  field  work. 

Km.!  \  P.  CuRRiE,  in  charge  of  editorial  work. 

Mabel  Colcord,  in  charge   of  library. 

2 


CONTENTS. 


Page. 

Introduction 5 

Generic  and  specific  synonymy  of  Prociphilus  tessellata  Fitch 6 

First  series:  Pemphigus  acerifolii  Riley 9 

Extracts  from  notes  made  at  the  time 11 

Second  series:  Pemphigus  tessellata  Fitch 14 

Extracts  from  notes  made  at  the  time 14 

Description  of  the  principal  stages  of  Prociphilus  tessellata  Fitch 18 

Sexual  generation 19 

Sexual  female 19 

Male 20 

Winter  egg 21 

Asexual  generations 21 

Colony  on  leaf  of  maple 21 

Young  stem-mother 21 

Mature  stem-mother 22 

Migrant 22 

Apterous  female  on  alder 23 

Hibernating  series 24 

Economic  status 25 

Index 27 


LLUSTRATIONS. 


Page. 

Fig.  1.  Prociphilus  tessellata:  Migrants  from  maple  to  alder 12 

2.  Prociphilus  tessellata:  Return  migrants  on  trunk  of  maple 16 

3.  Prociphilus  tessellata:  Sexual  female  and  antenna 19 

4.  Prociphilus  tessellata:  Male  and  antenna 19 

5.  Prociphilus  tessellata:  Colony  on  leaf  of  maple 20 

6.  Prociphilus  tessellata:  Young  stem-mother  and  antenna 21 

7.  Prociphilus  tessellata:  Mature  stem-mother  and  antenna 22 

8.  Prociphilus  tessellata:  Migrant  and  antenna 23 

9.  Prociphilus  tessellata:  Colonies  of  apterous  feaaales  on  alder .  24 

10.  Prociphilus  tessellata:  Colonies  of  apterous  females  on  alder 24 

11.  Gallery  made  by  the  ant  Cremastogaster  to  protect  colony  of  Prociphilus 

tessellata  on  alder 25 

12.  Prociphilus  tessellata:  Apterous  female  and  antenna. 25 

3 


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THE  LIFE  HISTORY  OF  THE  ALDER  BLIGHT  APHIS. 


INTRODUCTION. 

For  many  years  past  the  writer  has  spent  much  time  in  studying 
the  insects  of  the  family  Aphididiw  or  plant-lice,  in  the  office  and 
laboratory  and  in  the  field.  In  perhaps  no  other  group  of  insects  is 
a  thorough  knowledge  of  the  life  histories  so  necessary  to  correct 
conceptions  of  the  species  and  the  differences  between  them.  These 
life-history  studies  are  often  rendered  especially  difficult  from  the 
well-known  fact  that  many  of  these  aphides  have  a  secondary  or 
alternate  food  plant.  In  the  case  of  injurious  species  it  sometimes 
happens  that  the  main  injury  is  to  the  alternate  food  plant,  and  the 
discovery  of  the  primary  food  plant  furnishes  the  key  to  the  most 
effective  way  of  controlling  the  species.  A  notable  example  of  this 
is  the  hop  aphis  (Phorodon  hwrnndi  Schrank)  which  lays  its  eggs 
and  passes  the  winter  on  the  plum,  and  which  is  best  combated  by 
destroying  or  spraying  the  wild  or  cultivated  plum  trees  at  the 
seasons  of  the  year  when  the  aphis  is  present  on  this  food  plant, 
rather  than  by  measures  directed  against  the  insect  during  the 
summer  when  it  occurs  on  the  hopvines. 

The  writer  has  worked  out  the  life  histories  of  several  of  the 
aphides  which  have  alternate  food  plants.  Among  these  may  be 
mentioned  HormapMs  hamamelidis  Fitch  and  Hamamelistes  spino- 
sus  Shinier,  which  inhabit  both  the  witch-hazel  and  the  birch,1  the 
hop  aphis,  just  mentioned,  and  others. 

Investigations  by  the  writer  of  the  present  species,  which  has 
heretofore  been  confused  under  various  names,  were  begun  in  1878 
and  have  been  continued  up  to  the  year  1911.  They  have  resulted 
in  straightening  out  the  synonymy  of  the  species  and  furnished  con- 
clusive proof  that  the  Pemphigus  acerifolii  of  Riley,  described  from 
the  maple,  and  the  (Eriosoma)  Pemphigus  tessellata  of  Fitch,  de- 
scribed from  the  alder,  are  merely  forms  or  series  of  one  and  the 
same  species,  which  should  now  be  known  as  ProcipMLus  tessellata 
(Fitch). 

1  Tech.  Sor.  No.  9,  Div.  Eut.,  D.  S.  Dept.  Agr.,  1901. 


6  LIFE    HISTORY    OF    THE    ALDER    BLIGHT    APHIS. 

GENERIC    AND    SPECIFIC    SYNONYMY    OF    PROCIPHILUS    TESSEL- 

LATA   FITCH. 

Eriosoma  tessellata  Fitch,  Cat.  Ins.  [N.  Y.]  State  Cab.  Nat  Hist.,  p.  68,  1851. 

Aphis  stamineus  Haldeman,  Proc.  Boston  Sue.  Nat  Hist.,  vol.  «'».  p.  403,  1859. 

Schizoneura  tessellata  Thomas.  8th  Rept  Xox.  and  P.en.  Ins.  111.,  p.  139, 
1879. 

Pemphigus  tessellata  Osborn,  Can.  Ent,  vol.  14,  p.  61,  1882. 

Pemphigus  acerifolii  Riley,  Sth  Kept.  Xox.  and  Ron.  Ins.  111..  Suppl.,  p.  209, 
1S79. 

Pemphigus  alni  Provancher,  Petite  Fanne  Eutomologique  dn  Canada,  vol.  3, 
p.  320,  1S86. 

Prociphilus  Koch. 

The  genus  Prociphilus  was  described  by  C.  L.  Koch  l  in  1857,  and 
included  three  species.  The  following  is  a  translation  of  his  generic 
diagnosis: 

"Antenna. — Short:  the  two  basal  joints  as  usual,  short;  joint  3 
as  long  as  the  two  following  joints  combined  and  somewhat  uneven; 
joints  4  to  6  subequal  in  length;  spur  of  sixth  joint  thin  and  rather 
short. 

••  X<  ctcarii  8. — Wanting. 

"Anterior  wings. — Stigma  long  and  narrow:  the  stigma]  vein 
sliirhtlv  curved.  The  first  two  discoida]  veins  arising  close  together, 
though  not   from  the  same  point. 

"Legs. — Rather  stout  and  long." 

All  <>f  these  characters  agree  well  with  those  of  P.  tessellata  Fitch 
and  some  other  species. 

In  connection  with  the  above  description  it  seem-  necessary  to  add 
a  few  points  not  mentioned  by  Koch: 

Antenna]  joints  3  to  ">  or  6  more  or  less  densely  provided  with  trans- 
verse, elongate-ova]  sensoria,  not  reaching  the  lateral  margin. 

Venation  of  hind  wings  like  that  of  P<  mphigus;  the  two  discoida] 
vein-  arising  near  each  other  from  the  subcostal  vein  about  the  middle 
between  the  base  of  the  wing  and  the  booklet-,  at  a  point  where  the 
subcostal  bends  suddenly  toward  the  front  margin  of  the  wing,  giving 
it  the  appearance  of  three  discoida]  vein-  or  of  a  three-pronged  fork. 

Last  abdominal  segment  and  tail  semicircular  and  fringed  with 
-lender  hair-. 

Procip  hills  tessellata   Fitch. 

This  so  common  species  was  first  described  by  Dr.  A-a  Fitch.  State 
entomologist  of  the  State  of  New  York,  from  apterous  specimen- 
found  on  branches  of  alder  (Alnus  rubra),  in  hi-  catalogue  of  the 
Homoptera  of  the  State  Cabinet  of  Natural  History  of  the  State  of 
Xew  York.  1851,  page  68.  with  the  following  words: 

1  •'  Pflanzenlause  Aphiden,'*   p.  279. 


GENERIC    AND   SPECIFIC    SYNONYMY.  7 

"Alder  blight,  E.  tessellata.  Dull  bluish-black;  tergum  with  the 
segments  marked  by  strongly  impressed  lines  and  covered  by  white 
down  in  square  checker-like  spots.  Length,  0.16.  On  the  underside 
of  branches  of  the  alder  {Alnus  rubra,  Marsh.)  crowded  together  and 
concealed  beneath  a  dense  covering  of  snow-white  down.  I  have 
searched  in  vain  for  winged  individuals  of  this  species.     Xo.  863." 

A  few  years  later  Prof.  S.  S.  Haldeman  described  the  same  species * 
as  a  large  species  forming  follicles  on  the  leaves  of  the  silver-leaved 
maple,  Acer  eriocarpum  (of  which  Acer  dasycarpum  is  but  a  syn- 
onym).    He  refers  to  it  as  follows: 

"Aphis  (Pemphigus)  stamineus. 

"  This  name  is  proposed  for  a  large  species  of  Aphis  which  forms 
follicles  on  the  leaves  of  the  silver-leafed  maple  (Acer  eriocarpum  )." 

Prof.  Haldeman.  who  mistook  the  migratory  female  for  the  male, 
gave  the  following  description  of  the  insect : 

B Male. — Black,  feet  long,  slender,  and  rufous;  tarsi  biarticulate; 
wings  slightly  deflexed,  translucent,  pale  ferruginous  at  the  base, 
submarginal  nervure  conspicuous,  black,  and  ending  in  a  long  stigma ; 
disk  with  four  simple  nervures:  posterior  wings  with  three  nervures; 
mesonotum  polished,  with  a  deep  Y-shaped  impression;  abdomen 
without  tubes;  promuscis  obsolete,  antennae  (Particulate,  the  first 
two  short,  the  third  long,  and  the  fourth,  fifth,  and  sixth  gradually 
lengthening;  length  of  body,  H  lines,  or,  to  the  end  of  the  wings,  2^ 
lines. 

"Female  and  pupa. — Apterous,  dark-reddish  brown,  feet  paler; 
promuscis  twice  as  long  as  the  head,  thickened  near  the  apex;  length. 
H  lines." 

This  is  without  a  doubt  the  same  species  as  the  one  described  by 
Prof.  C.  V.  Riley  under  the  name  of  Pemphigus  acerifolii.  the  de- 
scription of  which,  for  the  benefit  of  those  interested  in  this  subject, 
may  be  here  reproduced. 

"PempMgus  acerifolii  Riley. 

".  Living  in  abundant  and  long  cottony  excretions  on  the  underside 
of  the  leaves  of  Acer  dasycarpum.  causing  them  to  curl,  and  exuding 
an  abundance  of  thick  and  very  glutinous  ;  honey-dew.' 

"  Winged  female. — Alar  expanse  16  mm.  Head  and  thorax  bluish- 
black.  Abdomen  black,  covered  with  long  cottony  threads.  An- 
tenna? reaching  the  wing  insertions;  ambulations  not  conspicuous; 
joints  3,  4,  5,  and  6  somewhat  contracted  at  base  and  apex;  apical 
unguis  not  perceptible;  joints  5  and  6  subequal:  -1  distinctly  clavate; 
3  as  long  as  the  two  preceding  together.     Wings  subhyaline,  of  a 

1  Troc.   Boston  Soc.   Nat.  Hist.,  vol.  6,  p.  403,   1859. 
25795°— No.  24—12 2 


8  LIFE   HISTORY    OF   THE   ALDER  BLIGHT   APHIS. 

whitish  tinge;  subcostal  vein  and  the  inner  margin  of  the  stigma 
black ;  oblique  veins  whitish,  stigma  short  and  broad,  not  angled  at 
the  base  of  the  stigmal  vein,  which  starts  from  a  little  behind  the 
middle  and  is  comparatively  straight,  thereby  making  the  apical  cell 
rather  narrow.  Terminal  distances  between  the  veins  subequal,  that 
between  second  discoidal  and  cubital  somewhat  greatest ;  basal  one- 
third  of  the  cubitus  hyaline,  but  not  abortive,  as  it  can  usually  be 
traced  to  its  base,  which  is  very  close  to  that  of  the  second  discoidal ; 
bases  of  the  two  discoidals  either  approximate  or  quite  contiguous; 
discoidals  of  the  hind  wings  proceeding  connectedly  from  the  sub- 
costal vein.  Larva  with  5-jointed  antenna3  and  the  promuscis  extend- 
ing beyond  tip  of  abdomen/' 

Prof.  Cyrus  Thomas  determined  the  alder  blight  as  Schizoneura 
tessellata,  and  gave  the  following  short  note  concerning  it: 

This  species  is  found  on  the  underside  of  the  branches  of  the  alder  (Ainu  ft 
rubra),  crowded  together  and  concealed  beneath  a  covering  of  snow-white  down. 
Wingless  individuals,  dull  bluish-black:  the  back  of  the  segments  are  marked 
with  strongly  Impressed  lines  and  covered  with  white  down  in  square,  checker- 
like  spots.     Length  to  tip  Of  the  abdomen,  0.16  inch. 

Prof.  IT.  Osborn,  on  account  of  the  simple  venation  of  the  wings, 
referred  the  species  to  the  genus  1\  mpMgus. 

Lastly,  it  was  described  under  the  name  of  Pemphigus  alni  by  the 
Abbe  L.  Provancher,  who  supposed  that  it  was  a  new  species.     The 

following  is  an  English  translation  of  the  French  original  descrip- 
tion : 

Pemphigus  of  the  alder.     r<  mphigus  alni. 

Length,  0.8  nun.:  to  the  tip  of  the  wings.  22  mm.  Dark  brown,  including  the 
head  and  legs,  covered  entirely  with  a  whitish  powder.  The  abdomen  is  covered 
with  a  long,  white,  and  woolly  secretion.  The  wings  are  transparent,  the  veins 
brown  and  strong:  stigma  elongated,  narrow;  radical  cell  elongate,  inferior 
veins  barely  curved. 

Pound  in  douse,  compact  masses,  several  Inches  long,  on  Alnus,  during 
September. 

Besides  the  above  extract-  pertaining  to  this  species,  it  may  be  ap- 
propriate to  mention  here  also  a  short  report  by  Dr.  Peter  Kalm,  a 
Swedish  naturalist,  of  whose  "  Travels  into  North  America  "  an  Eng- 
lish translation  has  been  published.  In  Volume  I,  second  edition 
(1772),  page  1'21.  there  is  the  following  account  of  an  insect  on  the 
alder,  noticed  by  him  while  traveling  through  Pennsylvania  and 
Delaware.  October  3,  1748 : 

I  saw  to-day  the  Chermes  of  the  alder  (Chermes  alni)  in  great  abundance  on 
the  branches  of  that  tree,  which  for  that  reason  looks  quite  white,  and  at  a 
distance  appears  as  it  were  covered  with  mould. 

The  above  lines  refer  undoubtedly  to  P.  tessellata,  which  Kalm 
mistook  for  the  European  insect  which  was  mentioned  by  Linnaeus 


FIRST   SERIES:   PEMPHIGUS    ACERIFOLII   RILEY.  9 

in  "  Fauna  Suecica,"  published  in  1746,  but  which  was  described  in 
the  "Acta  "  of  Upsala  in  1736  under  the  name  of  Chermes  alni  L. 
Later,  by  mistake  or  oversight,  Dr.  M.  Geoffroy  1  redescribed  this 
latter  insect  under  the  name  of  Psylla  viridis,  and  as  inhabiting  the 
alder,  without  recognizing  in  it  the  Chermes  alni  L.,  which  may  be 
considered  typical  of  the  genus  Psylla,  and  a  good  illustration  of 
which,  though  without  a  name,  will  be  found  in  "  Memoires  pour 
Servir  a  PHistoire  des  Insectes,"  Volume  III  (1737),  Plate  XXVI. 
figure  1,  by  M.  de  Eeaumur.  Another  figure  of  the  same  psyllid  was 
published  by  J.  H.  Sulzer 2  under  the  name  of  Chermes  alni  L. 
Evidently  this  psyllid,  from  a  distance,  bears  some  resemblance  to 
our  American  insect  P.  tessellata,  which  inhabits  the  American 
alders. 

Kalm  was  therefore  greatly  mistaken  when  he  supposed  that  our 
insect  was  the  same  as  the  European  Chermes  alni  L.,  or  rather,  as 
it  is  now  known,  Psylla  alni. 

Katzeburg3  refers  to  this  insect  in  the  following  words: 

Auf  Erlen  [alders],  ist  die  im  Puppenzustande  sehr  sonderbare,  kurzborstige, 
grime,  zuletzt  schwarzaftrige,  als  Fliege,  schon  grassgrmie  11'"  lange  /'.  alni  I,., 
welcbe  meist  in  der  Blattaehsel  ibren  Sitz  bat,  sehr,  ansgezeiclmet  durcb  lange 
weisse  Wolle,  welcbe  beweglicb  zu  werdeu  scbeint,  wenn  das  Insect  beunrnbigt 
wird. 

An  English  translation  of  the  above  would  read  as  follows: 

On  tbe  alders  are  found  very  curious,  green.  short>spined  pupae,  the  anal 
end  of  which  in  time  becomes  quite  black,  which  eventually  change  into  the 
1}  lines  long,  bright,  grass-green  Psylla  alni  L.  They  are  generally  stationed  in 
the  angles  formed  by  junctions  of  the  petioles  of  the  leaves  and  the  twigs.  The 
most  obvious  characteristic  about  them  is  the  very  long,  white  wool,  which 
appears  to  move  whenever  the  insect  is  irritated. 

All  of  the  above  facts  prove  that  the  European  Chermes  or  Psylla 
alni  L.  has  nothing  in  common  with  the  American  insect. 

FIRST  SERIES:    PEMPHIGUS  ACERIFOLII  RILEY. 

Observations  on  the  first  or  original  series  of  Pemphigus  acerifofii 
Riley,  inhabiting  the  soft,  or  silver  maple,  Acer  dasyearpum,  were 
commenced  by  me  in  1878  and  continued  until  the  year  1911,  whereas 
observations  on  the  alternating,  or  second  series,  of  Pemphigus  tes- 
sellata  Fitch,  inhabiting  the  alders,  were  started  in  1883,  or  about 
five  years  later  than  those  of  the  former. 

Pemphigus  acerifolii  issues  during  the  early  or  middle  part  of 
April,  or  as  soon  as  the  young  leaves  appear,  from  winter  eggs  de- 
posited the  previous  fall  in  cracks  or  under  loose  bark  on  the  trunks 

1  ITistoire  Abre^ee  des  Insectes,  vol.  t,  p.  486,  no.  3,  t799. 

2  Die  Konnzfichon  der  Insekten,  PI.  XII,  1761, 

3  Die  Forst-Insecten,  vol.  3,  p.  187,  1844, 


10  LIFE   HISTORY    OF   THE   ALDER   BLIGHT    APHIS. 

of  maples,  on  which  return  migrants  from  alders  had  delivered 
themselves  of  the  true  sexes. 

These  young  stem-mothers,  after  hatching  from  winter  eggs,  travel 
upward  onto  the  branches  and  settle  on  the  midrib  of  the  underside 
of  the  young  leaflets.  Usually  there  is  but  1,  though  frequently  there 
may  be  2,  3,  or  more  on  the  same  leaf,  in  consequence  of  which,  as 
well  as  from  the  increasing  irritation,  the  leaves  thus  infested  exhibit 
a  more  or  less  marked  tendency  to  fold  or  almost  to  M  double  up  n 
from  the  midrib  downward. 

Under  or  within  this  protection  or  covering  there  may  be  observed 
numbers  of  larva?  and  pupa?  of  different  stages,  up  to  100  or  more,  in 
company  with  their  mother,  all  of  which,  from  early  in  June  to  the 
end  of  July,  or  until  the  supply  for  migrants  has  been  exhausted, 
develop  into  winged  migrants,  without,  however,  leaving  any  larvae 
behind  to  continue  the  series  on  the  maple.  These  migrants  fly  then 
to  the  alders,  which  frequently  are  rather  distant  from  the  maples, 
and  settle  at  once  on  the  underside  of  the  leaves  of  these  shrubs,  where 
they  are  soon  engaged  in  depositing  their  larvae,  which  surround 
them  in  a  circle  of  about  *20  to  100.  These  larvae,  after  feeding  for 
about  an  hour  or  so.  move  to  the  twigs,  branches,  or  stems  of  the 
shrubs  to  start  a  new  cycle  of  life  for  the  species.  Here  a  number 
of  generations  is  developed,  after  which,  from  about  the  middle  of 
September  to  the  middle  of  October,  numerous  return  migrants  are 
developed,  which  fly  back  to  the  trunks  of  the  maples  to  continue  the 
cycle  of  life  prescribed  by  nature. 

In  consequence  of  these  facts,  which  were  gradually  obtained,  I 
have  been  able  to  prove  beyond  a  doubt  that  the  original  ho<t  plant 
of  this  species  is  the  silver  maple,  and  not,  as  might  be  supposed,  the 
alder:  the  latter  i>  its  secondary  food  plant,  and  proof  of  this  was 
establi>hed  during  June  of  1003. 

In  conjunction  with  the  above,  it  seems  proper  and  just  to  give 
some  of  the  observations  made  through  which  the  life  history  of  the 
species  was  definitely  ascertained. 

Besides  the  migrant-  from  the  maple  and  return  migrants  from  the 
alder.  I  ascertained  also  that  after  the  departure  of  the  return 
migrants  numbers  of  mature,  apterous  females  still  remain  upon  the 
alders  and  keep  on  producing  additional  larva\  all  of  which,  without 
casting  a  skin,  crawl  down  the  stems,  and  frequently  to  the  stouter 
roots,  which  are  more  or  less  surrounded  by  cavities  made  by  ants,  or 
hide  between  or  beneath  the  dead  leaves,  etc..  which  surround  the  base 
of  the  shrubs,  for  hibernation.  These  form  the  first  hibernating  series 
of  larva?  and  neither  feed  nor  irrow  until  the  sap  rises  again  the  follow- 
ing spring,  when,  after  an  absorption  of  sufficient  nourishment,  they 
cast  their  first  skin  and  keep  on  growing  until  mature,  at  which  time, 


FIEST   SERIES:   PEMPHIGUS    ACERIFOLII   RILEY.  11 

like  their  parents,  they  also  deposit  numbers  of  larva?,  which  in  turn 
reach  maturity. 

Multiplication  goes  on  in  this  way  until  a  second  series  of  migrants 
is  produced  the  following  fall  from  the  original  settlers.  However, 
there  remain  again  enough  apterous  females  to  produce  a  second 
series  of  hibernating  larvae,  to  produce  an  additional  series  of 
migrants.  A  third  series  of  migrants  and  hibernating  larva?  was 
also  traced. 

How  long  the  vitality  of  the  original  stock  will  last  it  is  impossible 
at  present  to  surmise,  though  it  seems  that  multiplication  may  go 
on  indefinitely  if  the  aphides  are  not  exterminated  by  carnivorous 
enemies  or  by  parasites. 

The  most  active  among  the  carnivorous  enemies  are  the  larva?  of 
the  lycaenid  butterfly  Feniseca  tarquinius  Fabricius;  the  larvrc  of  the 
lacewing  fly  Chrysopa  sicheli  Fitch  [  =  <°.  quad?n  punctata  Burmeis- 
ter] ;  the  larva?  and  imagos  of  two  ladybirds,  Hippodamia  convergent 
Gucrin,  and  Adalhi  h>  punctata  Linnauis;  the  larva?  and  imagos  of  a 
hemipteron,  (Xahis)  Pagasa  fusca  Stein,  besides  the  larva?  of  various 
syrphid  flies,  which  generally  prove  very  destructive  to  these  aphides 
and  frequently  exterminate  whole  colonies. 

Internal  parasites  are  thus  far  not  known. 

Besides  these  enemies,  there  are  various  species  of  ants  which  are 
mainly  attracted  to  these  aphides  by  the  honey  dew  ejected  by  them, 
upon  which  they  feed,  while  some  of  them  even  protect  the  aphides 
against  enemies  by  constructing  tubes  or  tunnels  of  earth  over  and 
around  such  colonies,  leaving  here  and  there  a  few  exits  open  to 
enable  the  ants  to  enter  and  leave.  The  ants  which  have  been 
observed  to  construct  tunnels  or  covers  over  these  aphides  are  Tapi- 
noma  sessile  Say  and  Cremastog  aster  lineolata  Say;  among  those 
which  simply  gather  honeydew,  Camponotus  pennsylvanicus  De  Geer, 
Lasius  alicnus  Forster,  and  Monomorium  minim/urn  Buckley  (minu- 
tum  Mayr)  have  been  observed. 

EXTRACTS    FROM    NOTES    MADE    AT   THE    TIME. 

Jane  28,  1883. — Migrants  from  maple  leaves,  placed  in  a  jar  for 
observation,  deposited  since  yesterday  a  large  number  of  larva?.  All 
of  them  were  provided  with  a  long  rostrum,  which  proved  that  they 
were  not  the  sexes  of  this  species. 

Found  to-day  two  colonies  on  leaves  of  maple  near  Ilosslyn,  Va., 
and  considered  the  migrants  in  these  colonies  at  that  time  as  being 
identical  with  those  of  Pemphigus  tessellata  Fitch,  though  notwith- 
standing that  migrants  were  flying,  I  failed  to  observe  any  of  them 
or  their  larvae  on  any  of  the  alders  examined.  However,  after 
placing  infested  leaves  of  maple  with  a  branch  of  alder  I  found, 
later  on,  that  two  of  the  migrants  had  settled  on  the  alder  leaves. 


12 


LIFE   HISTORY   OF    THE   ALDER   BLIGHT    APHIS. 


With  them  were  also  a  few  small  colonies  of  larva1  which  had  settled 
on  the  branch,  while  recently  deposited  larva?  were  also  observed  on 
the  leaves. 

June  7,  1904. — Received  to-day  from  Chatham.  Va..  some  leaves  of 
maple  infested  with  pupae  and  migrants  of  Pemphigus  aeerifolii.  A 
number  of  these  migrants  were  placed  with  a  potted  plant  of  alder 
for  observation,  and  I  found  the  following  day  that  quite  a  number 
of  these  migrants  had  settled  on  the  underside  of  some  of  the  leaves, 
and  with  them  were  many  voting  larva1  which  they  had  deported, 
all  of  which  proved  them  to  be  identical  in  every  respect  with  those 

of  P(  m pli  ig  us  ft  sseUata.  These 
larvae  were  reddish  or  brown- 
ish red  and  provided  at  the 
anal  end  of  the  body  with  a 
white  and  curly  or  cottony 
secretion,     which     gradually 


spread  over  the  whole  insect 
until  it  had  the  appearance  of 
a  little  lump  of  cotton. 

Migrant-  which  were  placed 
with  a  potted  maple  died  with- 
out depositing  any  larvae. 

JunA  -'•<.  1905.— Observed 
to-day  some  migrants  of  Pem- 
phigus aeerifolii,  on  the  un- 
derside  of  leaves  of  alders, 
Alias  rugosa,  near  the  Chain 
Bridge,  District  of  Columbia.' 
They  were  each  surrounded  by 
a  circle  of  about  28  larva1,  all 
of  which  had  already  cast 
their  first  skin,  which  was  ad- 
hering to  the  leaves.  These 
larva'  were  orange  and  their 
abdomen  covered  with  a  long 
and  backward-directed,  cottony  secretion,  whereas  that  of  the  thorax 
was  shorter  and  quite  erect,  longest  along  the  median  line.  Some- 
time- three  or  four  of  the  migrants  had  settled  on  the  same  leaf; 
some  of  them  were  already  dead  or  barely  living.  On  some  of  the 
leaves  were  several  ring-  of  cast  -kins,  varying  from  18  to  40  in  num- 
ber, while  on  the  branches  of  the  same  shrubs  were  numerous  larger 
or  smaller  colonies  of  larva'. 

April  IK  1905. — While  examining  trunks  of  maples  near  Rosslyn, 
Va..  T  found,  under  the  shaggy  bark  of  a  tree,  numbers  of  dead  and 
dry  return  migrants,  and  with  them  also  some  of  the  young  stem- 


Fig.  1. — ProciplMus  tessellata:  Migrants 
from  maple  to  aider.     (Original.) 


FIRST   SERIES:  PEMPHIGUS   ACERIFOLII   RILEY.  13 

mothers,  slowly  moving  about,  all  of  which  would  have  had  to  crawl 
5  to  10  feet  to  reach  the  nearest  branches.  Young  larva?  were  not 
yet  present,  though  the  buds  were  just  swelling. 

May  11, 1906. — To-day  I  saw  near  Rosslyn.  Va.,  a  few  young  stem- 
mothers  on  leaves  of  lower  branches  of  maples  stationed  near  the 
base  of  the  midrib  on  the  underside  of  the  leaves.  Two  of  them  were 
already  fully  grown  and  completely  covered  with  a  large  amount  of 
woolly  secretion,  irregularly  interspersed  with  rather  long  and  more 
or  less  curly  or  wavy  white  threads.  These  two  females  deposited  a 
few  larva?  till  the  day  following. 

May  18, 1906. — Found  at  Rosslyn.  in  the  same  locality  as  above,  six 
of  the  stem-mothers  on  one  of  the  maples.  With  one  of  them  were 
75  and  with  another  one  over  100  larvae,  which  were  already  of  two 
stages  and  of  a  pale  orange  color.  The  smaller  larva?  had  a  brush 
of  white  secretions  at  the  end  of  the  body,  whereas  the  whole  dorsum 
of  the  larger  or  older  larva?  was  covered  with  long,  white  wool,  inter- 
spersed with  twine-like,  wavy  strands. 

June  6,  1906. — A  lot  of  maple  leaves  badly  infested  with  Pemphi- 
gus aeerifolii  were  received  to-day  from  Fredericksburg,  Va.  Among 
Ihe  aphides  were  quite  a  number  of  migrants,  some  of  which  were 
placed  on  leaves  of  a  potted  alder  and  soon  settled  on  the  underside 
of  these  leaves.  On  examining  this  tree  in  the  afternoon  of  the 
next  day  I  found  that  one  of  the  migrants  had  deposited  a  consider- 
able number  of  larva3,  which  soon  after  were  seen  traveling  up  and 
down  the  stem. 

June  10,  1906. — Discovered  to-day  four  colonies  of  Pemphigus 
aeerifolii  on  leaves  of  maple  near  the  Chain  Bridge,  District  of 
Columbia.  The  infested  leaves  were  almost  folded,  both  halves  bend- 
ing down  from  the  midrib.  Inside  of  these  folds  were*  numbers  of 
pupa?  which  at  the  anal  end  were  provided  with  about  12  rather 
stout,  twine-like,  and  somewhat  wavy  or  curly  white  filaments,  about 
3  or  4  times  the  length  of  the  body,  spreading  out  fanlike,  inter- 
mixed at  their  bases  with  shorter,  fine  wool  or  secretion.  In  the 
immediate  neighborhood  numbers  of  migrants  were  alreadv  found 
on  the  leaves  of  alders  accompanied  by  a  brood  of  their  larva?, 
besides  numerous  colonies  of  larva?  on  branches  and  stems. 

June  18, 1906. — A  large  colony  of  larva?  from  migrants  of  Pemphi- 
gus aeerifolii,  which  had  settled  on  the  stem  of  a  potted  alder,  was 
greatly  reduced  by  pupa?  of  (Nobis)  Pagasa  fusca  Stein,  which  fed 
on  the  aphides. 

June  26,  1906. — Observed  to-day  numbers  of  migrants  from  maple 
on  the  underside  of  leaves  of  alders  near  the  Chain  Bridge,  District 
of  Columbia.  Many  of  them  were  already  dead,  though  all  others, 
still  living,  were  empty  and  shrunken.  Two  of  the  migrants,  alive 
and  active,  were  surrounded  by  numerous  larva?,  and  still  depositing. 


14  LIFE    HISTORY    OF    THE   ALDER   BLIGHT    APHIS. 

There  were  also  numerous  colonies  of  young  larvae  on  the  branches 
and  stems. 

May  28,  1911. — Found  to-day  one  colony  of  Pemphigus  acerifolii 
on  a  leaf  of  maple  near  Kosslyn.  Va..  containing  one  stem-mother 
and  135  of  her  progeny — mostly  pupa?,  in  various  stages  of  develop- 
ment— besides  many  quite  small  larvae,  while  the  mother  appeared 
to  be  in  a  condition  to  deposit  still  more. 

SECOND  SERIES:  PEMPHIGUS  TESSELLATA  FITCH. 

Notwithstanding  that  the  insect  under  this  name  had  been  known 
to  me  since  1869  as  having  a  range  from  Canada  to  Florida  and  as 
far  west  as  St.  Louis.  Mo.,  occurring  upon  native  and  foreign  species 
of  alders,  the  first  attempt  to  learn  its  life  history  was  begun  in 
June.  1883,  when  young  colonies  had  established  themselves  on 
branches  of  different  kinds  of  alders  on  the  grounds  of  the  Depart- 
ment of  Agriculture  at  Washington,  D.  C.  The  larva?  were  appar- 
ently the  progeny  of  migrants  from  maples  nearby.  They  had 
settled  on  the  underside  of  the.  branches  in  groups  of  4  to  8  speci- 
mens, arranged  in  circles,  with  their  heads  toward  the  center.  All 
were  covered  with  rather  long,  white  secretion,  so  as  to  resemble 
a  rosette,  or  a  single  insect,  reminding  one  strongly  of  some  of  the 
aleyrodids.  This  secretion  issues  from  G  rows  of  transversely  oval 
and  rather  flat  warts. 

Early  in  October  of  the  same  year  some  of  the  branches  were 
almost  completely  covered  with  colonies  12  or  more  inches  in  length. 
Among  tlit'  great  number  of  apterous  females  were  also  many  pupaj 
and  large  numbers  of  winged  specimens. 

EXTRACTS  FROM   NOTES  MADE    LT  THE  TIME. 

April  ..'s.  1897. — Observed  again  -mall  colonies  of  larva-  on  alders 
on  the  Agricultural  grounds.  All  of  them  were  densely  covered  with 
a  white  and  woolly  secretion,  intermixed  with  stout  and  curly  threads. 
They  were  closely  packed  and  resembled  colonies  of  large  mealy- 
bug-, arranged  more  or  less  in  circles;  sometimes  they  were,  however, 
so  much  crowded  that  many  were  actually  standing -on  their  heads. 
These  larvae  had  apparently  been  hibernating  since  the  previous  fall. 

September  /..'.  1897. — Found  large  colonies  of  this  insect  on  alders 
at  Cabin  John.  Md.,  and  among  them  numerous  pupa?  and  migrants. 
The  winged  specimen^  were  densely  covered  with  long,  white  tufts 
of  secretion,  which  formed  a  dense  mass  on  the  dorsum  and  around 
the  end  of  the  body,  besides  projecting  in  shaggy  tufts  above  the 
closed  wings.  This  secretion  was  intermixed  at  the  anal  end  of  the 
body  with  longer  and  stouter  threads;  along  the  sides  of  the  abdomen 
were  rather  long,  delicate,  and  somewhat  curly,  erect  tufts  or 
streamers,  and  also  long  and  forwardly  directed  tufts  on  the  thorax 


SECOND   SERIES:    PEMPHIGUS    TESSELLATA   FITCH.  15 

and  head,  whereas  the  ventral  side  of  the  body  was  densely  covered 
with  a  short  and  white  secretion. 

September  14,  1897. — A  lot  of  migrants  from  alders  were  placed  in 
a  tube  to  obtain  their  progeny.  By  the  following  day  they  had  de- 
posited a  number  of  larvae  which,  on  examination,  proved  to  be  the 
sexes,  or  males  and  females,  of  this  species,  both  of  them  without 
a  rostrum.  The  females  were  about  twice  as  large  as  the  males  and 
of  a  bright  yellow,  whereas  the  males  were  greenish  or  greenish 
yellow.  The  antennae  and  legs  of  both  were  colorless.  Each  of  the 
females  contained  only  one  egg. 

Most  of  the  males  were  dead  about  7  days  later,  whereas  most  of  the 
females  were  still  alive,  active,  and  mature.  These  females  had 
cast  four  skins,  which  in  most  cases  were  still  attached,  in  a  con- 
tinuous string,  to  the  end  of  the  body.  None  of  the  females  had  in- 
creased in  size,  and  they  looked  the  same  as  before.  Some  had 
secreted  a  quantity  of  rather  long  and  woolly  secretion,  which  covered 
the  posterior  half  of  the  body. 

September  21,  1897. — On  examining  the  trunks  of  maples  near 
Rosslyn,  Va.,  I  discovered  one  of  the  sexual  females  in  a  crack  of  the 
bark,  in  the  company  of  a  migrant  from  alder. 

September  SO.  1897. — Examined  the  trunk  of  a  European  alder  on 
the  Agricultural  grounds,  the  branches  of  which  were  still  covered 
with  this  insect;  on  the  trunk  were  also  a  few  migrants,  though  I 
failed  to  find  any  of  the  sexes  or  the  winter  eggs :  there  were,  however, 
on  the  rough  bark  and  tucked  away  in  cracks  or  cavities  large  num- 
bers of  hibernating  larvae,  while  others  were  still  coming  down. 

November  5,  1897. — Reexamined  the  same  tree,  and  found  again 
numerous  hibernating  larva1  in  cracks  and  in  empty  egg-cases  of 
spiders,  but  none  of  the  sexes  or  winter  eggs;  these  larva1  were  either 
covered  with  a  bluish-white  secretion  or  ornamented  with  G  dorsal 
rows  of  squarish,  mealy  patches,  giving  them  a  pretty,  checkered 
appearance. 

After  an  unavoidable  intermission  of  a  number  of  years,  observa- 
tions on  this  particular  aphis  were  again  taken  up  in  1903. 

January  11,  1903. — While  again  examining  alders  on  the  Agricul- 
tural grounds,  large  numbers  of  colonies  of  this  species  were  seen 
on  the  shoots,  all  of  them  being  covered  with  cottony  secretion.  On 
examining  these  colonies  it  was  found  that  all  of  the  apterous  females 
were  dead,  having  evidently  been  killed  by  the  late  frosts,  but  under- 
neath them,  and  between,  were  found  live  and  active  hibernating 
larvae,  which  evidently  had  been  protected  against  the  wintry  blasts 
by  the  covering  of  their  dead  mothers. 

September  27\  1905. — A  few  colonies  on  alder  were  found  near  the 
Chain  Bridge,  District  of  Columbia,  and  among  them  numbers  of 
return  migrants. 


16 


LIFE   HISTORY   OF   THE   ALDER  BLIGHT   APHIS. 


October  5, 1905. — Large  numbers  of  return  migrants  were  found  on 
the  trunks  of  many  of  the  maples  near  Rosslyn,  Va.,  while  on  alders 
near  by  some  colonies  of  Pemphigus  tcssellata,  composed  of  apterous 
females,  accompanied  by  numerous  larva1  of  the  hibernating  series 
and  numbers  of  return  migrants,  were  observed.  A  comparison  of 
these  migrants  with  those  found  at  the  same  time  on  the  trunks  of 
maples,  or  with  those  of  the  first  series,  termed  Pemphigus  acerifolii, 
proved  them  to  be  absolutely  alike.  These  return  migrants  to  the 
maples  were  scattered  over  the  trunks  of  the  trees  from  the  bottom 

to  at  least  50  feet  above 
the  ground,  or  as  far  up  as 
the  eye  could  reach,  re- 
sembling flakes  of  snow. 
Frequently  as  many  as  20 
or  more  were  counted  in 
some  of  these  batches. 

With  the  migrants  were 
also  numbers  of  the  true 
sexes,  many  of  them  in 
copula.  Some  of  these 
females  had  crowded  into 
such  small  cracks  that  it 
seemed  almost  impossible 
for  them  to  do  so;  3  1  speci- 
mens of  both  sexes  were 
found  between  and  under 
some  old  spider  webs,  while 
near  them  under  a  small 
piece  of  loose  bark  were 
110  of  the  sexual  females, 
closely  packed.  There 
were  also  winter  eggs  in 
groups  of  two  or  more, 
^lightly  covered  with  or 
embedded  in  a  delicate 
layer  of  white  wool.  The 
empty  females  were  colorless  and  generally  died  some  distance  from 
their  egg.  though  sometimes  a  dead  female  was  found  with  the  egg 
still  attached  to  it. 

July  19,  1906. — Near  the  Chain  Bridge,  District  of  Columbia. 
Failed  to  find  Pemphigus  acerifolii  on  leaves  of  maple,  nor  were  any 
migrants  observed  on  leaves  of  alders.  I  discovered,  however,  3 
colonies  of  the  hibernating  series,  some  of  which  were  already  ma- 
ture females,  accompanied  by  hundreds  of  young  larva*,  distributed 
in  patches  of  5  to  10  or  more,  all  arranged  in  circles,  with  their 


Fig. 


—Prodphilua   teaselata:  Return  migrants 
on  trunk  <>f  maple.      <  Original,  t 


SECOND   SEKIES:   PEMPHIGUS   TESSELLATA  FITCH.  If 

heads  directed  toward  the  center,  each  specimen  being  ornamented 
with  six  rows  of  shaggy  or  threadlike  secretion. 

October  15,  1906. — After  examining  thousands  of  alders  near  the 
Chain  Bridge,  District  of  Columbia,  only  three  colonies  were  discov- 
ered, composed  of  apterous  females  and  their  larva?  situated  near 
the  surface  of  the  ground  on  the  steins,  each  of  which  was  completely 
covered  with  a  tube  of  mud  constructed  by  the  small  ant  Tapinoma 
sessile  Say.  I  saw,  however,  on  the  trunks  of  large  maples,  thousands 
of  dead  return  migrants  and  the  sexual  generation  belonging  to  them. 

November  26,  1907. — Observed  again  near  the  Chain  Bridge  num- 
bers of  hibernating  larva?  between  the  dead  and  decavino-  leaves  which 
had  accumulated  around  the  base  of  a  small  shrub.  All  of  them  were 
quite  lively,  though  not  feeding.  They  were  very  dark  greenish  or 
almost  black,  covered  with  a  mealy  secretion,  and  provided  with  a 
cotton-like  brush  at  the  anal  end  of  the  body. 

March  11,  1908. — Numbers  of  hibernating  larvae  were  found  near 
Somerset.  Md.,  which  had  gathered  around  the  base  of  the  shrubs, 
though  still  covered  with  fallen  leaves,  while  smaller  colonies  had 
already  settled  from  1  to  4  feet  above  the  ground,  arranged  in  circles 
'of  5  to  10  specimens.  All  were  covered  with  a  bluish- white  secretion 
and  had  4  dorsal  rows  of  small  dense  and  rounded  white  knobs  and 
a  fringe  of  woolly  secretion  along  the  sides  and  around  the  anal  end 
of  the  body. 

May  14-  1908. — Found  again  near  Somerset  one  small  colony,  about 
2  feet  above  the  ground,  composed  of  mature  apterous  females  of  the 
hibernating  series,  besides  numbers  of  young  larva?  deposited  by  them 
which  had  settled  near  by  while  others  were  still  crawling  about. 
These  young  larva?  form  the  third  generation  of  descendants  from 
migrants  of  the  previous  spring. 

June  12, 1908. — Numbers  of  colonies  of  the  hibernating  series,  each 
colony  being  about  one-half  an  inch  in  length,  were  seen  at  Great 
Falls,  Va.,  on  small  shrubs.  They  were  about  10  inches  above  the 
ground,  whereas  those  on  taller  trees  had  located  10  to  25  feet  above 
the  ground.  All  of  them  were  already  in  the  third  stage,  were  closely 
packed,  and  covered  with  a  fuzzy  secretion.  Migrants  from  maples 
were  not  present. 

September  2i,  1908. — Numerous  colonies  of  this  species  were  again 
observed  on  alders  near  Somerset,  Md.  Some  of  the  colonies  were 
more  than  G  inches  in  length  and  were  stationed  from  near  the  ground 
to  2  feet  above.  They  were  composed  of  apterous  females,  numerous 
larva?  of  the  hibernating  series,  pupa?,  and  some  return  migrants, 
while  at  the  same  time  a  considerable  number  of  these  return  migrants 
and  many  of  the  sexual  generation  were  found  on  the  trunks  of 
maples  along  a  street  near  by. 


18  LIFE   HISTORY   OF   THE  ALDER  BLIGHT   APHIS. 

October  IS,  1908. — Examined  some  tall  alders  near  Rosslyn,  Va., 
on  which  migrants  from  maples  had  settled  in  spring,  and  found 
four  colonies  about  10  feet  above  the  ground.  These  colonies  were 
from  6  to  10  inches  long  and  contained  apterous  females  and  numer- 
ous larvae  destined  for  hibernation.  They  were  crawling  down  the 
stems  to  the  base,  where  they  congregated  in  a  dense  mass,  while  a 
great  many  were  already  in  hiding  between  the  fallen  leaves  near 
the  base  of  the  trees.  There  were  also  many  of  the  return  migrants, 
which  were  crawling  to  the  tip  of  the  branches  or  to  the  terminal 
leaves,  on  which  they  settled,  ready  for  migration. 

April  27,  1909. — Examined  again  the  above  alders  near  Rosslyn 
and  found  that  some  specimens  of  the  hibernating  series  were  already 
in  the  second  and  third  stages. 

In  the  youngest,  or  first  stage  the  antenna?  are  distinctly  4-jointed; 
in  the  second  stage,  after  eating  a  skin,  they  are  5-jointed;  they  are 
also  5-jointed  in  the  third  stage,  though  the  divisions  between  the 
joints  are  much  more  distinct. 

June  15,  1909. — Observed  some  migrants  of  Pemphigus  acerifolii 
and  their  larva1  on  the  underside  of  leaves  of  alders  and  numerous 
colonies  of  such  larvae  on  the  stems  or  trunks  of  such  shrubs  from 
1  to  10  feet  above  the  ground,  at  Great  Falls.  Va.  (Early  in  October 
of  the  same  year  large  colonies  were  seen  on  the  same  alders,  about 
4  to  15  feet  above  the  ground,  composed  of  apterous  females,  accom- 
panied by  numerous  larva1  of  the  hibernating  series  which  were 
swarming  down  the  stems,  and  numbers  of  the  return  migrants.) 

J  urn  29.  1910. — Saw  again  numbers  of  migrants  of  Pemphigus 
acerifoMi)  with  recently  deposited  larva1  near  them,  on  the  underside 
of  leaves  of  alder  near  Somerset.  Md.,  while  numbers  of  migrants 
were  still  living  about.  There  were  also  numbers  of  colonies  of 
apterous  females  belonging  to  the  hibernating  series  and  numerous 
larva1  deposited  by  them. 

September  17.  1910. — Numerous  colonies  of  Pemphigus  tessellata, 
about  4  feet  above  the  ground,  were  again  found  on  alders  near 
Somerset.  They  were  composed  of  apterous  females  and  their  larvae, 
besides  pupa1  and  return  migrants.  Many  of  these  colonies  were 
being  preyed  upon  by  larva  of  Feniseca  tarquimus,  as  well  by  larvae 
of  coccinellid  and  chrysopid  insects.  Many  of  the  apterous  females 
descended  during  October  to  the  base  of  the  shoots  or  stems,  even  as 
far  down  as  1  or  2  inches  below  the  surface,  where  they  were  sur- 
rounded by  numerous  liberating  larva,  constituting  a  second  series. 
All  of  these  colonies  were  covered  with  tunnels  of  clay  constructed 
by  Cremastog  aster  lineolata  Say. 

DESCRIPTION   OF  THE  PRINCIPAL  STAGES  OF  PROCIPHILUS   TES- 

SELLATA  FITCH. 

In  view  of  the  fact,  as  has  already  been  stated,  that  the  spring 
migrants  from  the  maple  to  the  alder  and  the  return  fall  migrants 
from  the  alder  to  the  maple  are  absolutely  identical  and,  as  a  rule, 


DESCRIPTION    OF   PRINCIPAL    STAGES. 


19 


destined  to  continue  and  to  conclude  the  yearly  cycle  of  life  for  the 
preservation  of  the  species, 
the  following  descriptions 
of  some  of  the  principal 
stages  are  herewith  in- 
cluded. 

SEXUAL    GENERATION. 


The  larva-like  sexes  of 
the  species,  which,  toward 
the  end  of  September  and 
early  in  October,  occur  on 
the  trunks  of  maples,  are 
rather  small  and  without 
a  rostrum  for  the  absorp- 
tion of  food. 

SEXUAL    FEMALE. 


FIG.    3. 


-Prociphilus  tcssellata:  Sexual  female 
and  antenna.      (Original.) 


The    sexual    females,    as 

found  under  loose  bark  of 

maple,  are  of  an  orange  color,  with  the  sides  of  the  body  more  or 

less  distinctly  grayish 
green.  They  are  elon- 
gate-oval and  rather 
plump,  and  contain  only 
one  large  orange  egg, 
which  reaches  to  the 
prothorax.  The  legs 
and  antenna?  are  whit- 
ish; the  eyes  small  and 
black.  The  posterior 
lateral  angles  of  the 
prothorax  and  of  the 
first  abdominal  segment 
are  rather  prominent, 
while  similar  though 
smaller  angles  are  also 
present  on  all  of  the 
other  abdominal  seg- 
ments except  the  termi- 
nal one.  The  antennae 
are    rather    short     and 

reach  for  a  short  distance  beyond  the  anterior  margin  of  the  meso- 


FlG.    4. 


-Prociphilus   tessellata:   Male   and   antenna. 
(Original.) 


20 


LIFE    HISTORY    OF    THE   ALDER    BLIGHT   APHIS. 


thorax:  they  are  5-jointed;  joint  3  is  shortest  and  joint  5  longest,  or 
about  as  long  as  joints  3  and  4  combined:  joints  1.  2.  and  4  are  some- 
what longer  than  3.  but  shorter  than  5,  and  subequal  in  length.  All 
of  the  tarsi  of  both  sexes  are  provided  with  short,  capitate  digitules. 
Length,  about  1.2  mm. 


Fig.    5. — Prociphilu*    tesaellata:    Colony    on    leaf    of    maple. 
(Original.) 


The  male  is  of  a  more  or  less  greenish  color,  with  its  antenna?  and 
legs  somewhat  dusky.  It  is  rather  small  and  about  one-third  or  less 
the  size  of  the  female.  The  antenna^  are  about  as  long  as  those  of  the 
female,  though  stouter,  while  the  proportion  of  the  length  of  the 
various  joints  is  the  same  in  both  sexes.    Length,  about  0.8  mm. 


DESCRIPTION    OF    PRINCIPAL    STAGES. 


21 


WIN TEE    EGG. 


The  winter  eggs,  especially  in  the  vicinity  of  Washington,  D.  C, 
are  generally  deposited  during  the  first  half  of  October,  in  cracks 
and  under  loose  bark  of  the  trunks  of  silver  or  soft  maples,  where  they 
are  embedded  in  delicate  white  wool.  They  are  highly  polished  and 
at  first  of  an  orange  color,  with  a  greenish-gray  central  spot,  though 
they  change  gradually  to  a  blackish  green.  They  are  elongate-oval 
and  almost  twice  as  long  as  wide.  Their  length  is  about  0.7  mm., 
and  the  diameter  0.4  mm. 

ASEXUAL   GENERATIONS. 


COLONY    OX    LEAF    OF    MAPLE. 

As  had  been  stated  before,  it  has  been  demonstrated  that  the  in- 
fested leaves  on  maple  trees 
exhibit  a  more  or  less  distinct 
tendency  to  fold  or  to  double 
downward,  so  as  to  protect 
the  insects  within  this  fold,  in 
which  frequently  there  is  a 
large  and  closely  packed 
colony  of  aphides,  covered 
with  a  cottony  secretion  which 
gives  the  entire  mass  a  re- 
semblance to  a  large  white- 
haired  caterpillar. 

YOUNG    STEM-MOTHER. 

The  general  color  of  the 
young  >tem-mother  i>  a  dull 
blackish  or  brownish  green, 
the  head  being  darkest.  The 
eyes  are  black  and  the  antennae 
and  legs  dusky.  The  insects 
are  covered  with  a  delicate 
bluish-white  secretion,  and  ornamented  with  four  dorsal  and  a  lateral 
row  each  side  of  whitish  cottony  knobs.  The  antenna1  are  4- 
jointed  and  do  not  reach  to  the  mesothorax:  the  two  basal  joints  are 
shortest :  joints  3  and  4  are  longest  and  subequal  in  length,  each  being 
about  as  long  as  the  two  basal  joints  combined:  the  third  is  some- 
what stoutest  at  the  apex,  while  the  fourth,  including  its  short, 
blunt  spur,  appears  to  be  more  or  less  distinctly  fusiform.  The  ros- 
trum is  large,  and  reaches  almost  to  the  tip  of  the  abdomen.  Length 
about  0.7  mm. 


Fig.    6. — Prociphilua    tcssellata:    Young    stem- 
mother  and  antenna.     (Original.) 


22 


LIFE    HISTORY   OF    THE   ALDER   BLIGHT    APHIS. 


MATURE    STEM-MOTHER. 


The  mature  stem-mother,  as  seen  on  the  leaves  of  the  maple,  is 
densely  covered  with  white  wool,  which  is  interspersed  with  long, 
stout,  white,  and  wavy  strands.  This  secretion  hides  the  insects  com- 
pletely from  view,  in  consequence  of  which  they  resemble  small 
flakes  of  cotton.  Their  natural  color  is  dark  yellowish  green  or  olive ; 
the  end  of  the  body  is  black:  the  legs  are  of  the  color  of  the  body, 
with  the  apex  of  the  femora  and  tarsi  blackish.  The  antennae,  includ- 
ing the  indistinct  spur  of  the  terminal  joint,  are  5- jointed:  they 
are   rather   short    and    reach    about   to   the  mesothorax.      The    first 

joint  is  stoutest  and  slightly  the  short- 
est; it  is  about   as  long  as  wide,  with 
(l^tl!^-^^^        the  apex  truncated;  joints  *2  and  4  arc 

somewhat  longer  than  the  first  and  sub- 
equal  in  length;  joints  3  and  5  are 
longest  and  each  of  them  is  almost  as 
long  as  the  two  basal  joints  combined; 
the  four  basal  joints  are  of  the  color 
of  the  body,  while  the  fifth  is  blackish. 
Length  of  body  about  4  mm.;  diameter 
about  3  nun. 

The  mature  stem-mother  deposits  be- 
tween 100  and  400  larvae,  all  of  which 
form  the  first  generation,  which  may 
l»c  termed  the  pupiferous  generation, 
since  all  of  them  gradually  develop  into 
the  winged  or  migratory  form  and, 
after  having  attained  maturity,  migrate 
to  the  leaves  of  alders  to  deposit  their 
larva',  which,  in  turn,  become  the  pro- 
genitor- of  the  second  series,  which  has  been  described,  by  Dr.  Asa 
Fitch  under  the  name  of  Eriosoma  tesseUata. 


Fig.  7.  Prociphilus  tessellata: 
Mature  Btem-mother  and  an- 
tenna.     (Original.) 


MIGRANT. 


The  migrant,  as  well  as  the  return  migrant,  is  rather  large  and 
stout.  The  head  with  its  antenna?,  the  thorax,  and  the  legs  are 
black.  The  abdomen  is  of  a  greenish -brown  or  almost  black  color; 
being  palest  on  the  ventral  side.  The  dorsum  of  the  thorax  and  of 
the  abdomen  is  densely  covered  with  a  whitish  woolly  or  cottony 
secretion,  which  generally  projects  above  the  closed  wings  and  be- 
yond the  end  of  the  abdomen,  while  most  of  the  secretion  of  the  head 
is  generally  rubbed  off.     The  ventral  side  is  covered  with  a  whitish 


DESCRIPTION    OF    PRINCIPAL   STAGES. 


23 


powder,  which  is  most  dense  on  the  sternum.  The  antennae  are  rather 
short  and  reach  to  or  somewhat  beyond  the  insertion  of  the  front 
wings;  they  are  provided  with  only  a  few  fine  hairs  on  joints  3  to  5; 
there  are  also  9  to  13  annulations  on  antennal  joint  3,  3  to  5  on  joints 
4  and  5,  and  from  5  to  T  on  joint  6,  all  of  which  annulations  are  more 
or  less  indistinct.  The  tail  and  last  abdominal  segment  are  short 
and  semicircular,  surrounded  around  the  edge  with  slender  fine  hairs. 
Xectaries  or  nectar-pores  are  absent.  The  venation  of  the  wings  is 
similar  to  that  of  other  pemphiginids.  Expanse  of  wings  about  12 
mm. ;  length  of  body  about  4=  mm. 


Pig.  8. — Prodphilua  tessellata:  Migrant  and  antenna.      (Original.) 


APTEROUS   FEMALE   ON   ALDER. 


The  apterous  females,  as  found  on  the  stems  of  alder,  are  densely 
covered  with  white  woolly  or  cottony  secretion,  which  gradually 
covers  a  whole  colony,  though  frequently  hidden  from  view  by  a 
covering  of  earth  erected  over  them  by  Cremastog aster  and  other 
ants.  After  having  been  denuded  of  their  cottony  secretion  they 
are  found  to  be  of  a  reddish  or  dark  orange-brown  color,  with  the 
divisions  between  the  abdominal  segments  much  darker  or  almost 


24 


LIFE    HISTORY    OF    THE   ALDER    BLIGHT    APHIS. 


black:  the  antenna?  and  legs  are  the  color  of  the  body  and  the  tarsi 
are  blackish.  The  antenna?  are  G-jointed.  rather  short,  and  reach 
at  most  to  the  middle  of  the  mesothorax.  Antennal  joints  3  and  6 
are  longest  and  subequal  in  length,  each  being  about  as  long  as  joints 
±  and  5  combined:  joints  1.  2.  4.  and  5  are  shortest  and  subequal  in 
length,  with  the  two  basal  joints,  as  usual,  stoutest;  all  of  the  joints 


1 


FiO.    9. — Colonies    of    apterous    females 
on  alder,      i  Original,  i 


Fig.  10. — Colonies  of 
apterous  females  on 
alder.     (Original.) 


are   provided   with   a   few   fine   and   short   hairs.     The  tail   and   last 
abdominal  segment  are  as  in  the  migrant.    Length  about  3  mm. 


HIBERNATING    SKRIES. 


The  hibernating  larvae,  a-  well  a-  those  deposited  by  migrants  and 
apterous  females,  are  of  an  orange  color,  with  the  eye^  and  tarsi  dark- 
brown  or  black;  all  of  them  are  covered  with  a  short  and  shaggv 
secretion.  The  antenna?  are  4-jointed  in  all  of  them :  they  are 
short,  as  usual,  and  reach  to  nearly  the  middle  of  the  mesothorax. 


ECONOMIC   STATUS. 


25 


The  first  joint  is  shortest,  stoutest  at  the  apex,  and  about  one-half 
the  length  of  the  second;  joint  3  is  longest,  rather  slender,  though 
somewhat  stoutest  at  the  apex;  joint  4  is  next  in  length  and  about 
twice  as  long  as  the  second.  The  rostrum  is  almost  as  long  as  the 
body.     Length  about  1  mm. 

ECONOMIC   STATUS. 

This  species  may  not  be  considered  as  particularly  injurious,  though 


Fig.  11. — Tunnel  made  by 
the  ant  Cremastogaster  to 
protect  colony  of  Pro- 
ciphilus  tessellata  on  alder. 
(Original.) 


Fig.    12. 


-Procipliilus   tessellata:   Apterous   female   and 
antenna.      (Original.) 


it  may  occasionally  become  quite  annoying  if  present  in  numerous 
colonies  on  the  leaves  of  maple  trees,  in  consequence  of  which  it  may 
be  advisable  to  suggest  some  method  for  keeping  it  down,  if  not 
actually  exterminating  it,  in  certain  localities.  To  accomplish  this 
result  it  is  advisable  to  cut  down  all  of  the  shrubs  of  alder  during 
the  spring  and  fall  to  near  the  surface  of  the  ground  and  to  burn 
all  of  the  bush  as  soon  as  possible,  in  order  to  destroy  all  of  the 


26  LIFE   HISTORY   OF   THE  ALDER  BLIGHT  APHIS. 

colonies  as  a  measure  to  prevent  the  maturing  of  the  return  migrants. 
Still  later  in  the  season  it  is  advisable  to  spray  all  of  the  remaining 
stumps  of  the  shrubs,  as  well  as  the  accumulated  dry  leaves  and  other 
debris  surrounding  them,  with  a  dilute  solution  of  kerosene  emulsion, 
in  order  to  destroy  the  hibernating  larva?.  If  these  shrubs  are  kept 
down  for  a  few  years  there  will  be  no  chance  for  the  migrants  from 
maples  to  deposit  their  larva?  and  consequently  no  return  migrants 
to  fly  back  to  the  trunks  of  maple  trees. 


INDEX 


Acer  (see  also  Maple).  Page. 

dasycarpum=Acer  eriocarpum 7 

original  food  plant  of  Prociphilus  tessellata 9-14 

Adalia  bipunctata,  enemy  of  Prociphilus  tessellata 1> 

Alder  (see  also  Alnus). 

alternate  food  plant  of  Prociphilus  tessellata 14-18 

blight  aphis.     (See  Prociphilus  tessellata.) 

food  plant  of  Psylla  alni 9 

Alnus  (see  also  Alder). 

rubra,  food  plant  of  Prociphilus  tessellata 6,  7 

rugosa,  food  plant  of  Prociphilus  tessellata 12 

Ants  associated  with  Prociphilus  tessellata 11 

Aphis  stamineus,  description  by  Haldeman 7 

=  Prociphilus  tessellata 6 

Birch,  food  plant  of  Hamamelistes  spinosus 5 

Hormaphis  hamamelidis 5 

Camponotus  pennsylvanicus,  association  with  Prociphilus  tessellata 11 

Chermes  alni.     (See  Psylla  alni.) 

Chrysopa  quadripunctata,  enemy  of  Prociphilus  tessellata 11 

sicheli—  Chrysopa  quadripunctata 11 

Cremasiogaster  lineolata,  association  with  Prociphilus  tessellata 11, 18,  23,  25 

Ei iosoma tessellata.     (See  Prociphilus  tessellata.) 

Feniseca  tarquinius,  enemy  of  Prociphilus  tessellata 11, 18 

Ilamamelisies  spinosus,  food  plants 5 

Ilippodamia  conrergens,  enemy  of  Prociphilus  tessellata 11 

Hop,  alternate  food  plant  of  Phorodon  h  umuli 5 

aphis.     (See  Phorodon  humuli.) 

Hormapltis  hamamelidis,  food  plants 5 

Kerosene  emulsion  against  alder  blight  aphis 26 

Latins  alienus,  association  with  Prociphilus  tessellata 11 

Maple  (see  also  Acer). 

silver-leaved.     (See  Acer  eriocarpum. ) 

Monomorium  minimum,  association  with  Prociphilus  tessellata 11 

minutum=Mofwmorium  minimum 11 

Nabisfusca.     (See  Pagasafusca.) 

Pagasa  fusca,  enemy  of  Prociph ilus  tessellata 11.  13 

Pemphigus  acerifolii,  description  by  Riley 7-8 

—  Prociphilus  tessellata 5,  6 

'////  i,  description  by  Provancher 8 

=  Prociph  ilus  tessellata 6 

stamineus.     (See  Aphis  stamineus.) 

tessellata= Prociphilus  tessellata 6 

Phorodon  humuli,  food  plants 5 

Plum,  original  food  plant  of  Phorodon  humuli 5 

27 


28  LIFE    HISTORY    OF    THE   ALDER    BLIGHT   APHIS. 

Page. 

Prociph  ilus,  description  of  genus 6 

tessellata,  ant  associates 11 

apterous  female  on  alder,  description 23-24 

asexual  generations,  descriptions 21-25 

colony  on  leaf  of  maple,  description 20,  21 

description  b y  Fitch 6-7 

of  principal  stages 18-25 

economic  status 25-26 

first  series  (Pemphigus  acerifdii  Riley) 9-14 

generic  and  specific  synonymy 6-9 

*             hibernating  series,  description 24-25 

insect  enemies 11 

male,  description 20 

mention  by  Kalm  as  Cht  run  %  alni 8-9 

migrant,  description 22-23 

notes  on  alternate  series 14-18 

original  series 11-14 

second  series  (on  alder) 14-18 

sexual  female,  description 19-20 

generation,    description 19-21 

stem-mother,  mature,  description 22 

young,   description.. 21 

winter  egg 21 

PtyUa  "Ini,  description  by  Ratzeburg,  on  alder 9 

viridi8=(  fu  rmes  alni 9 

Schizoru  "/•</  tesseHakt,  description  by  Thomas 8 

=Prociph  Uus  te*8t  Uata 6 

Syrphid  fly  larva-,  enemies  of  Prociphilus  tateUata 11 

Tapinoma  a  drib  ,  association  with  Prociphilus  tessellata 11,17 

Witch-hazel,  food  plant  of  Hamamdistes  tpinosus 5 

Hbrmaphis  hamamelidis 5 


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